Access unit for use in underfloor duct systems



Sept. 26, 1961 G. E. BLINN ETAL ACCESS UNIT FOR USE IN UNDERFLOOR DUCTSYSTEMS Original Filed Jan. 28, 1955 2 Sheets-Sheei 1 M Mags ACCESS UNITFOR USE IN UNDERFLOOR DUCT SYSTEMS Original Filed Jan. 28, 1955 Sept.26, 1961 G. E. BLINN ETAL 2 Sheets-Sheet 2 IN 762 g, cm, mics/Mn: 44%

rT ATTOR YS United States Patent Ofi ice Re. 25,042 Patented Sept. 26,1961 25,042 ACCESS UNIT FOR USE IN UNDERFLOOR DUCT SYSTEMS Glenn E.Blinn, Teaneck, NJ., and Charles Flachbarth,

deceased, late of Narberth, Pa, by Charles T. Flachbarth, executor,Springfield, Pa.; said Glenn E. Blinn and Charles Flachbarth assignorsto Walker Brothers, Conshohocken, Pa., a corporation of Pennsylvania No.2,824,578, dated Feb. 25, 1958, Ser. No. 484,784, Jan. 28, 1955.Application for reissue Feb. 3, 1959, Ser. No. 791,784

7 Claims. (Cl. 138-92) Matter enclosed in heavy brackets I: appears inthe original patent but forms no part of this reissue specification;matter printed in italics indicates the additions made by reissue.

This invention relates to duct systems for electrical wiring installedin the floors of buildings and is concerned more particularly with anovel access unit for use in such systems to provide access to theinterior of the ducts. The new unit may be employed to particularadvantage in underfloor duct systems, in which selected cells of amulticellular steel floor provide wiring raceways, and a form of the newunit for use in such systems will, accordingly, be illustrated anddescribed in detail for purposes of explanation.

In underfloor duct systems, in which cells of a multicellular floor areemployed as Wiring raceways running in one direction, the circuit wiringis brought to such raceways from wall cabinets or boxes through headerducts, which lie upon and extend across the cells. The header ducts areprovided with access openings at selected points and frequently theopenings are uniformly spaced by a distance equal to a whole multiple ofthe distance between the centers of adjacent ducts. An access unit isemployed to close each opening in the header duct and the unit extendsupward through the concrete forming the floor and its top lies flushwith the floor surface. 'It is desirable that such an access unit beadjustable in height, and it should be capable of easy installation, sothat a unit may be placed in position whenever access to the system at anew location is necessary after completion of the system.

The access unit of the invention can be easily installed in an openingin the duct of an underfloor duct system, such as a header duct, and itis readily adjustable, so that it may be increased or decreased inheight as required by variations in the thickness of the floor materialabove the duct, in which it is mounted. The unit is so constructed that,in the pouring of the concrete of the floor, no concrete can enter theunit and the duct, and adjustments in the height of the unit can be madeeither before or after the concrete has been poured, since the adjustingmeans lie wholly within the unit and thus out of contact with theconcrete.

For a better understanding of the invention, reference may be made toaccompany drawings, in which FIG. 1 is a view in perspective of aportion of a duct system of the invention;

FIG. 2 is a vertical sectional view on the line 2-2 of FIG. 1;

FIG. 3 is a top plan view of one of the access units of the header duct;and

FIG. 4 is a view of the access unit in side elevation with parts brokenaway.

In the duct system shown in FIG. 1, cells of a multicellular floorgenerally designated 10 are used as circuit wiring raceways and thenumber and location of the cells employed for the purpose depends uponthe use to be made of the floor area and the specific requirements ofthe occupants. Multicellular floors are commonly made of sections, eachcomprising an upper corrugated metal sheet 11 and a similar lower sheet12 secured together in reversed relation as by welding to form a seriesof long cells 13, which serve as hollow beams and are connected byflanges 14. The sections of the floor are made in varying lengthsaccording to the dimensions of the building frame structure and adjacentsections are provided with interlocking parts 15 for holding thesections in position relative to each other. In the erection of thebuilding, the floor sections are placed with their ends supported on thebeams of the frame structure and the sections are ordinarily disposedwith their cells in alignment so as to form continuous raceways from onewall of the building to the opposite wall.

In the duct system illustrated, the cell 16 is used as a raceway and thecircuit wiring is brought to the raceways through header ducts from theusual wall cabinets or boxes, where the wiring is connected to thefeeder cables. One of the header ducts is shown at 18 and each headerduct lies upon the top of the multicellular floor transversely of thecells and is secured to the floor in any desired way as by strapsattached at their ends to flanges of the floor and extending over thetop of the duct. At one or both ends, a header duct may have an elbowsection 19 leading upward to a wall cabinet and, when it is desired toprovide an extension 20 of a duct leading, for example, to a column, asection of the duct may be removed and replaced by a box 21 of T-shapehaving aligned openings for receiving the ends of the duct and a sideopening receiving the end of the extension.

Each header duct is provided with top openings, through which access tothe interior of the duct can be had, and such openings lie above cellsof the floor. At the time of installation of the system, the bottom ofeach header duct may be connected to the cell beneath each accessopening, although, in some systems, such connections may not all be madein advance of the completion of the floor. The number of access openingsand their spacing along a header duct depends upon the number andspacing of the cells of the floor to be used as raceways. For somepurposes, the header ducts are provided with access openings at 12"spacings while, in other ducts, the spacing is 18", 24", etc. In allducts having access openings at a uniform spacing, the spacing is awhole multiple of the distance between the axes of adjacent cells of thefloor.

Floor structures, in which multicellular steel floors are employed, arecompleted at the top by concrete poured upon the steel floor to fill thespaces between the cells and form a layer providing the top floorsurface. At each access opening, the header duct has an access unit,which serves as a closure for the opening and extends up through theconcrete with its top lying flush with the floor surface. As theconcrete layer may vary in thickness for various reasons, as, forexample, because extra material was required to level the floor surfacein an area where the steel floor sagged under the weight of theconcrete, the access units are adjustable in height through asubstantial range and such adjustment can be readily made before orafter "the concrete has set.

Each access unit of the invention comprises a sleeve 23 which has asection 23a lying within the access opening in the top of the duct. Whenthe access unit is installed at the factory, the section 2321 of thesleeve used is longer than the thickness of the duct wall and the end ofthe section projecting into the duct is forced outwardly to provide asection 23b engaging the inner surface of the duct around the opening.Above section 23a, the sleeve has a section 23c extending radially fromthe opening and lying in contact-with the upper surface of the duct anda cylindrical section 23d extends upward from the outer edge oftheradial section 23c. When the sleeve is mounted as described, itprovides a smooth surface within the access opening.

A ring 24 is supported .adjustably within the cylindrical section 23d ofeach sleeve 23 and, for this purpose, three screws 25 are mounted toextend through openings in the section 23c of the sleeve and enterinternally threaded openings through internal bosses 24a on the ring 24.Each screw has a flared head at its lower end, which lies in contactwith the top wall of the duct 18. Thus the screws 25 have a fixed axialposition and are captive in that they are retained by the member inwhich they are mounted for free, non-threaded rotation. The upper end ofthe screws .are slotted to receive a screw driver inserted through theupper end of the openings receiving the screws.

Near its top, the ring is provided with an internal flange 26 forsupporting a .cover plate 27, which rests on a gasket 28 on the flangeand is held in place by screws 29 passed through openings in the plateand threaded into bosses 29a extending inwardly from flange 26. Ininstallations, in which the cover plate and the top of ring 24 lie flushwith the floor surface indicated at 30 and the floor surface is bare,the tops of screws 29 lie in the level of the top of the cover plate 27.In installations, in which a layer 31 of linoleum or like floor coveringmaterial is placed upon the top of the floor, a metal dish 32 having adepth equal to the thickness of layer 31 and a flat bottom may be usedwith the cover plate. A disc 33 of the floor covering material fills thedish and the screws 29 then pass through bushings 34 in the disc andthrough the disc and cover plate and gasket into flange 26.

Beneath each access opening, the header duct and the raceway cells areconnected through aligned openings. As the wiring is drawn through 'theducts and into the cells about the edges :of these openings, it isdesirable to provide smooth internal surfaces for the openings. thispurpose, a split grommet 35 of residient metal is collapsed to passthrough each pair of aligned openings in the Walls of the duct and celland is then released so that, upon expansion, its flanges 35a, 35b willproject radially from the openings and lie within the duct and cell.

In some installations of duct systems, it may be necessary to enlargethe system by utilizing .as raceways cells of the floor, which do notlie beneath access openings of the header ducts. When such a needarises, a hole is made in the floor to expose a portion of the ductabove the cell, to which the conection is to be made, and an accessopening 'is then cut through the .top wall of the duct and alignedopenings are similarly cut through the bottom wall of the duct and thetop wall of the cell by a suitable tool. A modified form of the newaccess unit is installed in the top opening and the unit used is thesame in all respects as the unit illustrated in FIG. 2 except thatits'sleeve 36 has-a section 36a, which extends through the opening inthe'top of the duct but has no section extending radially withinthe'duct'from 'the opening and corresponding to section 23b. The sleeve36 has a radial section'36a' resting on "the top of the'duct andcorresponding to section 23cand,*in order to secure 'the unit in placein the opening 'in the duct, openings are drilled through section 56a ofthe-sleeve and the wall of the duct and For self-locking rivets 37 areinserted in the openings tolock the sleeve in place.

In underfloor duct systems of the type described, the number of andlocation of the cells of the multicellular floor used as circuit wiringraceways and the number of and location of the header ducts will dependon the use to which the floor space is to be put. The number of andlocation of the access openings in the ducts will be determined by thenumber and location of the cells serving as parts of the system. In theinstallation of the system, the multicellular floor is laid in the usualway and the header duets with the access units in place are placed uponthe floor and secured in position as described. The floor is thencompleted by the pouring of the concrete and, during this operation, theconcrete cannot enter the access units, since the ring 24 of each unittelescopes snugly within sleeve 23 or 26. After the concrete has beenpoured, the cover plates are removed from the access units lying abovethe cells which are to be used as raceways, and the connections betweenthe ducts and the cells are cut and the grommets inserted. The coverplates may then be returned to position and, when necessary, the rings24 of the access units are adjusted by screws 25 to bring the tops ofthe units flush with the floor surface. This adjustment of the height ofthe units is simple, since the screws 25 lie within the units and arethus out of contact with the concrete.

We claim:

1. A header duct for use with a multicellular floor which comprises flattop and bottom walls, side walls connecting the top and bottom walls,the top wall having at least one opening, a sleeve mounted in theopening and extending upward, a closure for the sleeve mounted within itand movable vertically, and means within the sleeve and operable throughthe top of the closure for adjusting the position of the closurelengthwise of the sleeve.

2. The header duct of claim 1, in which the sleeve has a bottom sectionlying within the opening, a radial section connected to the upper end ofthe bottom section and overlying the duct top wall around the opening,and a top section extending upward from the outer edge of the radialsection, the closure comprises a ring and a cover plate having alignedopenings, the openings through the ring being threaded, and theadjustment means are screws extending through openings through theradial section of the sleeve and into the threaded openings through thering, the tops of the screws being slotted and being accessible throughthe openings through the cover plate for rotation to vary the verticalposition of the closure in the sleeve.

3. An access unit for closing an opening in a duct of an underfloor ductsystem, which comprises a sleeve adapted to be secured to the top of theduct to surround the opening and having a radial, inwardly-extendingsection and a top section extending upwardly from the outer portion ofthe radial section, a ring disposed telescopically within the topsection of the sleeve, a plurality of adjustment screws mounted withinthe sleeve in both the radial section of the sleeve and the ring andlying parallel to the axis of the sleeve, the screws being rotatable tocause the ring to move vertically upwardly and downwardly relative tothe sleeve, whereby rotation of the screws will cause relative verticaladjustment of the ring relative to the sleeve, said adjustment screwshaving the same axial position when being rotated to move the ringupwardly as when they are rotated to move the ring downwardly, and acover plate attached to the ring to close the upper end thereof.

4. The access unit of claim 3, in which the adjustment means are screwsextending into threaded vertical openings through the ring and havingslotted upper ends, the cover plate has openings in axial alignment withthe adjustment screws, and the slotted upper ends 0) theadjustmentscrewsare accessible through 'the openings in the cover plate.

References Cited in the file of this patent or the original patentUNITED STATES PATENTS 740,663 Krantz Oct. 6, 1903 6 Richardson et a1Apr. 14, 1925 Walker June 9, 1931 Sharp Sept. 5, 1933 Sharp Mar. 6, 1934Bissell et a1. June 9, 1936 Walker Dec. 8, 1936 Wiesman July 13, 1948Wiesman Oct. 27, 1953 Wiesman Mar. 23, 1954 Kennedy Sept. 18, 1956FOREIGN PATENTS Canada Mar. 6, 1951

